Combined railway electric traction, telegraph, and signal system.



I v. T. DAY. COMBINED RAILWAY ELECTRIC TRAGTION, TELEGRAPH, AND SIGNALSYSTEM.

APPLICATION FILED SEPT. 15, 1906.

Patented Jan. 19, 1915.

2 SHEETS-SHEET 1.

. Jkuerztor ll z'nessea." @mx lww W. cm W A. V. T. DAY. OOMBINEDRAILWAYELECTRIC TRACTION, TELEGRAPH, AND SIGNAL SYSTEM.

APPLICATION FILED SEPT. 15, 1906.

N M ENA MN Dzventor:

Witnesses: @MJ

ALBERT v. r. DAY, or new YORK, n. "r,

HALL swr'rcrr & SIGNAL ooiuraNY, or NEVJ roan, n. 2., A conrona'rronMAINE.

rants ASSIGNOR, BY MESNE ASSIGNMENTS, TO OF COMBINED RAILWAY ELECTRICTRACTION, TELEGRAPH, AND SIGNAL SYSTEM.

Specification of Letters Patent.

Patented Jan. 319, 1915.

Application filed September 15, 1906. Serial No. 334,733.

. means for railways, employing rail circuits an? periodic current forcontrolling the signa s.

My object is to provide signaling means peculiarly advantageous in itsadaptation to railways in which the track rails are also employed asconductors for periodic traction current, or periodic telegraph current,or both, and I have illustrated such an adaptation of my invention intwo sheets marked Left part of Fig. 1- and Right part of Fig.1, whichare to be read together as one drawing.

In this instance one of the track rails or L traflic rails R iscontinuous and the other traflic rail S is divided into signal blocks orsections by means of suitable insulations in this instance, locatedsubstantially at the signaling stations E and J respectively. Thecurrent for railway motive power or traction and for the telegraphsystem, and also electric current for operating all the block signalingapparatus of the system, are supplied from a power station which I havemarked P and which, in the illustrated instance, is located at theterminus of the railway track. The system includes a thirdrail Tadjacent to the railway track and divided into sections by suitableinsulations interposed, in the present instance, at the telegraphstations M and Q. The sections into which the third-rail T is thusdivided are much longer than the sections into which the signal rail Sis divided by its insulations at the signaling stations. These blocks orsections of the third-rail T will be hereinafter designated asthird-rail blocks or sections, or telegraph blocks or sections, incontradistinction to the shorter blocks or sections of the signal railS.

Each insulation in the signal rail S is spanned by an impedance coilsuch as 3, 3

'3, etc., at the various signaling stations, and

the insulations in the third-rail T are similarly spanned by impedancecoils 30" and 30? located substantially at the tele raph stations M andQ; and thereby the signal rail S and the third-rail T are renderedconductively continuous for unidirectional or non-periodic currentalthough the impedance coils effectually isolate the successive railsections from each other as regards inter-transmission of currentcomponents characterized by periodic variation.

The continuous track rail R, and the block signal rail S which is alsoconductively continuous for unidirectional motive power current, areboth employed as return conductors for the motive power or tractioncurrent. These track rails are cross-com nected by impedance coils suchas 2, 2, 2 etc., located midway between successive block signal stationsand acting as cross bonds for unidirectional current while at the sametime impeding the transmission of periodic current from rail to rail.The unidirectional or direct current traction generator is, of course,grounded on both the track rails R and S, and delivers current to a linefeeder extending out along the railway line. The successive sections ofthe third-rail T are fed by the line feeder p through impedance coils7f, 32 and 32, the first impedance coil 19 being located substantiallyat the power station I and the inipedance coils 32 and 32 being locatedrespectively at the telegraph stations M and Q. In addition, thesuccessive sections of the third-rail are fed by each other through theimpedance coils 30 30, etc., which unite such third-rail sections forinter change of unidirectional current.

An alternating current generator 3') is located at the power station P,and delivers alternating current to a transmission line including twoconductors g and y) extending out along the railway line. blocksignaling apparatus at the signalaw' stations B, C, D, E, F, G, H, I,and J are all the same, wherefore the block signal apparatus at thesignaling stations B and C may be described as representatives of theapparatus at the other stations. The signaling apparatus at each stationexcepting A includes a transformer comprising primary and secondarycoils such as 5 and 4 .respecth-ely, each primary coil being fed fromthe alternating current transmission line wires p and 1) and eachsecondary coil being connected with the track rails of the signal blocknext in the rear. The secondary coil, such as f of each transformerfeeds alternating current to the rail circuit of the signaling blocknext in rear, such rail circuit of the block B (1' being traceable asfollows: from one terminal of the secondary coil 4 to the advance end ofthe section B U of the signal rail S, thence rearward through suchsection of the signal rail S to the rear end of the block B C and thencethrough the alternating current relay mag net 7* and the condenser 6,both included in the signal apparatus B, and from the condenser 6" tothe continuous track rail R and thence forward through such track railto the advance end of the block B C and back to the opposite terminal ofthe secondary coil 4. Current from the secondary coil 4 traverses theforegoing rail circuit when there is no train or railway vehicle presentin the block B C, and, excepting leakage current which passes from railto rail through the ground and ties, substantially all of thealternating current from such secondary transformer coil 4 traversessuch rail circuit, because such alternating current is effectuallyimpeded or refused by the impedance coils 3, 2 and 3 The condenser 6included in the foregoing rail circuit and its relationship to thealternating current relay 7", constitute an important feature of myinvention whereby very important results are attained, as will bedescribed shortly hereinafter.

If a train or railway vehicle were present in the block B G, thealternating current from the secondary coil 4: of the transformer wouldbe short-circuited by the wheels and axles of the train or vehicle andpass freely from one track rail to the other, thus being shunted aroundthe relay 7" so as to effectually prevent the relay from beingenergized. Under these conditions the contact linger 8 of the relay'isheld by any suitable rctractiveforce outof engagement with itscooperating contact stop 9*, so as to maintain the signal semaphore 10in its danger position indicating that the block B C is occupied. Butwhen there is no train present in the block B C the rear track relay 7of such block is energized by alternating current flowing through thecircuit already traced, so as to maintain its contact finger 8 incontact with the cooperating stop 9 and thus maintain a flow of currentthrough the semaphore-actuating-orretaining electric-mechanism includedin series with the contacts 8*, 9 in a local branch circuit bridgedacross the alternating current line conductors 7), 2 Thus the signalingapparatus at the signal station B always indicates the condition of theblock B C, the semaphore 10 of such signaling apparatus being known as ahome signal.

To those schooled in the art it will be apparent how the signalingapparatus at any one or more of my signaling stations can besupplemented by an additional semaphore controllable by the condition ofthe signal block second in advance thereof, such an ad ditional signalsemaphore being known as a distant signal. Such distant signals and theadditional circuits or apparatus necessary to control them have beenomitted from my drawings simply for the sake of greater clearance in theillustration of-the more important rudiments of my invention.

The capacity of the condenser 67 and the inductance of the alternatingcurrent relay 7 7 are relatively adjusted for resonancewith thealternating or periodic current employed in the block-signaling railcircuit. This adjustment discharges a most unique and valuable functionwhich can most aptly be explained by a comparison with the old styleunidirectional-current or battery-current block signaling systems wellknown in the prior art. In these battery systems it has been customaryto connect a battery with the track rails at the advance end of thesignaling block and to connect what is known as the rear track relaywith the rails of the same signaling block at the rear end of the block.When no train is present in the signaling block the battery currentflows from the advance end of the block through the rails and throughthe rear track relay so as to clear the signal controlled by such relayat the rear'end of the block. Obviously, in such prior systems, thesignaling current encounters only the ohmic resistance of the relay atthe rear end of the rail circuit, but even so, it has been found thatwhen the signaling block is very long or when the ground and rail tiesare very wet, leakage from rail to rail through the ground and ties isso great as to effectually shunt current from the rear track relay sothat it will not clear the signal when the block is clear, unless abattery of consider-- able strength is employed. Now, .when we apply analternating current to the rails at the advance end of thesignalingblock, in lieu of a unidirectionalcurrent, the forego-' ingdifficulty is greatly augmented because added to the ohmic resistance ofthe relay we have its inductive resistance, so called, or its ceunter E.M. F. of selfrmduction, so

- mamas? ductive branch. The conditions make it GX-V ceedingly diflicultto operate a rear track relay through a trafiic-rail circuit with analternating current when the signaling block is long or when it issubjected to wet weather, unless. an exceedingly strong current isdelivered to the rail circuit to make good the excessive leakage. But myprovision of capacity adjusted relative to the track relay in resonancewith the block signaling current attains that same relationship ofimpedances through the track relay and through the leakage branch fromrail to rail, which relationship is attained in the old battery blocksignal circuits; and by means of my invention therefore it is possibleto clear a block signal through a trafiicrail circuit positively andreliably and without employing an excessive signal-clearing current atthe advance end of the rail circuit to make up for the enormous leakagefrom rail to rail.

Another important function and result of the adjustment of my condenserand track relay in resonance with the block signaling current, is thesaving in the expense of the block-bonding impedance coils such as 3,3", etc., employed to connect the adjacent sections of the blocksignaling rail S, and a, saving in the resistance losses in the returncircuit of the motive power current, and also a saving in the expense ofthe cross-bonding impedance coils such as 2 2, etc. The resonantadjustment of the rear track relay and its condenser, by reducing theimpedance through the relay branch to the ohmic resistance of suchbranch, makes it possible to operate the track relay with a much lowervoltage of block signaling current than the voltage which would berequired in the absence of such resonant adjustment. By thus reducingthe block-signaling difference of potential between opposite railsrequired to operate the block signal, my resonant adjustment of relayand condenser makes it possible to employ block-bonding and crossbondingimpedance coils of much lower 1mpedance and hence much less expensive incost of construction and also less wasteful of motive power energy in-the return path of the motive power current. Since these block-bondingand cross-bonding impedance coils are employed to prevent passage ofblock signaling current between ad acent sections of thesig'nal rail Sand between such signal rail and the continuous rail it, it is obviousthat the more the voltage or the block signaling current is reduced, the

more we may reduce the size and expense of the impedance coils withoutimpairing their foregoing functions.

Another important function and result of the adjustment of my condenserand tracl: relay in resonance with the block signaling current, is theselective responsiveness oi? such relay to the alternating or periodiccurrent of that particular frequency employed for clearing itsparticular block signals, and in discrimination against all otheralternating or periodic currents such as the alternating or periodiccurrents employed in my telegraph system, or periodic currents whichmight be employed in the traction system in lieu of the unidirectionalcurrent eniploycd in that embodiment of my invention which- I havespecifically illustrated. in the event of an accidental break in one ofthe track rails, which act as conductors for the telegraph current andthe traction current as well as for the block signal current,

or in the event of some other derangement distinctly difi'erent from theperiodicities or frequencies of all other periodic currents employed inmy system. Should a current higher in frequency than such distinct blocksignaling current attempt to pass through the relay '4', it would bestrongly impeded by the counter E. M. F. of the relay which, at suchhigher frequency, would be only partly neutralized by the counter E. M.l

of the condenser; and should the relay be subjected to a current lowerin frequency than the distinct block signaling current to which itresonantly responds, such current of lower frequency would beeffectually opposed by the counter E. M. F. of the con denser which, atsuch lower frequency, would be only partially neutralized by theinductance of the relay. Thus the relay branch from rail to rail refusesto conduct in substantial degree any current other than the particularblock signaling current to which the relay responds in resonance.

In addition to the fixed telegraphic stations M and Q of the telegraphsystem, 1 11a) illustrated three moving telegraph stations Y, J N, thosemoving telegraph stutions of the telegraph system being carried onmoving trains or railway vehicles. for which reason the three stationswill be here inafter or convenience referred to as the trains K, L, N.The trains l and are represented in the telegraph block P M, that is tosay, they are represented in that portion or section of the railwaytrack extending from the power station P to the fixed telegraph stationM, and through which railway block the first third-rail section extends.The train N is represented in the telegraph block M, Q, extending fromthe telegraph station'i /i to the telegraph station Q; and comprisingthe third-rail section M, Q. The wheels and aXles of the trains K, L,and N, are represented respectively at 2", 2, and 2, showing that thesetrains are located respectively in the signaling blocks A, B, G, D andG, H. The trains take current from the third-rail T through theirrespective third-rail shoes 5, and 5, such shoes being connected withthe conductors 4*, 4', and l, leading to the apparatus on the respectivetrains, and the apparatus on each train is connected with the axles andwheels of the train by means of conductors such as 3, 3, and 3 on thethree trains respectively.

Each train receives motive power or traction current from the third-railthrough a circuit which may be traced, for example, on the train K, asfollows: from the thirdrail T, through the third-rail shoe 5, conductor4*, fields 7 of the train motor, armature 6* of the train motor,conductor 3 and wheels and axles 2* to the traflic rails R and Swhich,as already pointed out, constitute a return circuit to the powerstation. Each train carries also a rotary converter or motor-generatoradapted to convert current from the traction generator at the powerstation P into current suitable for sending telegraphic communicationsor other signals from the train to a point outside the train, Themotorgenerator in this instance comprises a direct current motorarmature and two alternating current generator armatures. Considering,for instance, the apparatus of the train K, it will be noted that thetraction current passes through the shoe conductor at, thence throughthe fields 9 of the mtor-generator, motor armature 8 of themotor-generator, and thence to the grounded conductor 3*. The fieldwinding 9 may be employed to excite not only the motor-armature 8 butalso the two alternating current generator armatures 10 and 14 Thesegenerator armatures 10 and 148 are connected in respective parallelbranch circuits leading from the shoe conductor 11 to the groundedconductor 3*, through respective signal keys 13 and 17 and theirstationary contact members 12 and 1G and 80" the condensers 11 and andthe armatures 10 and lat connected in series with such condensersrespectively and with their signal'keys. Each train carries also tworeceiving instruments such as the receiving sounders 18 and 24* of thetrain K, connectmanner edin parallel branch circuits between theshoe-conductor 4 and the grounded conduetor 3 These parallel sounderbranches include condensers 19 and in series with the Sounders 18 and24: respectively, and

include also respective controlling switches sounder magnets bysufiicient magnetization thereof.

The fixed stations M and Q of the telegraph system comprises apparatuscorre sponding substantially to that carried by the moving trains,excepting the traction motors, third-rail shoes and the wheels and axlesof the trains, which are, of course, omitted at the fixed stations. Atsuch fixed stations M and Q, the grounded conductors 3" and 3 areconnected directly vwith the continuous track rail R, and the conductors4 and 4:, corresponding to the shoe conductors of the trains, areconnected directly Withrespective telegraph sections of the third-railT.

Not all the foregoing apparatus of the telegraph system is essential tovthe rudimental operation of my invention, nor is it essential that theapparatus shall be embodied" in the specific forms illustrated anddescribed, since any equivalent may be substituted for the sounder orfor the condenser or for any other element. For instance, to exemplifyone operation of my invention, it may be assumed that all the apparatuson the train K is dispensed with excepting the sounder 24 its condenser25*, its soundercontrolling switch-26, the conductor 4 leading tothethird'rail shoe, the grounded conductor 3 leading to the wheels andaxles, and the traction motor 6*; Now the traction motor 6* will receivemotive power current passing in the usual way from the third-railthrough such motor and to the traiiic rails included in. the return pathof the current;

but the traction current, which in this instance is a unidirectionalcurrent, will not pass through the sounder 249 because its condenser 25will not transmit such traction current. The condenser 25 will, however,transmit a periodic or alternating telegraphic or signaling current toand through the sounder 24; whereby the train K may receive signals ortelegraphic intelligence from another station, for instance, from thefixed station M of the telegraph system, through a circuit traceable asfollows: From one brush or terminal of the alternating current generatorarmature 14 of the motorgenerator at the station M, through thecondenserv 15", contact stop 16*, signaling meets? or telegraphic key17, conductor 4" leading to the third-rail section P M, thence throughsuch third rail section to the shoe 5 carried by the train K, and thencethrough. the shoe conductor at on such train, the sounder-controllingswitch 26 condenser 25*, sounder an, grounded conductor 3 wheels andaxles 2 and continuous track rail R to the grounded conductor 3* at thestation M and through such grounded conductor 3' back, to the oppositebrush or terminal of the alternating current generator armature 14 Thealternating current thus delivered by the generator armature 14, throughthe foregoing circuit and its receiving sounder 24 may be of such highfrequency that the sounder armature 27* will not be recovered by itsretractile spring :29, between successive current pulsations, but willbe held down against its stop 28 so long as the sending key 17 ispressed against its contact stop 16".

Obviously, by the foregoingor equivalent means, telegraphic intelligenceor other sig-' nals may be transmitted to the train K through itssounder 24 or through any signal receiving device equivalent thereto inthe broad aspect of my invention. And such signals may be transmitted inthe foregoing instance, regardless of the relationship of inductance andcapacity in the sounder and its condenser 25, providing only that the E.M. F. of the telegraphic current is high enough to force through thecondenser and the sounder a suificient current to eii'ectually magnetizesuch sounder and attract its armature. Therefore, my bread invention isin no wise limited to a resonant adjustment or to any other adjustmentof inductance and capacity in the sounder or equivalent device and itscondenser, although a resonant adjustment of such inductance andcapacity is highly advantageous in various ways. For instance, if analternating traction current be employed in lieu of a unidirectionaltraction current, the sounder and its condenser may be adjusted'inresonance with a particular signaling current of the telegraph system sothat the sounder will respond readily to such particular current whileits armature and retractile spring will be adjusted to avoid anyresponse to the alternating current of the traction system which willflow with comparatively weak intensity against the unbalanced countercl'cctromotive forces of inductance and capacity which are not adjustedin resonance with such traction current. Also when two sounders areprovided, such as the sounders 24 and 18" on the train K, in order toreceive simultaneously two messages or signals from one or more pointsoutside the moving train, each sounder and its respective condenser maybe adjusted relatively to each other resonanw with one of twoalternating or periodic currents of ditlerent frequencies. In thisinstance a given sounder will-resonantly respond to its own particularperi odic or alternating current while itsarma' ture will be adjusted toavoid response to the periodic current which resonantly operates theother sounder and which will flow in comparatively weak degree throughthe given sounder. Thus, distinct simultaneous messages or signals maybe received on one of the moving trains or at one of the fixedstationsoi? the telegraph system. The simultaneous messages thus received at onestation of the telegraph system may emanate from two other stations ofthe system or may both emanate from one other station of the system, andin order that two messages may be simultaneously sent from one station Ihave provided each station of the telegraph system with means forgenerating and controlling two periodic currents of differentfrequencies adapted for transmission of intelligence to one or moredifierent stations of the system, such means being embodied, in thepresent instance, in the motor-generators each having two generatorarmatures controlled by respective sending keys.

As an advantageous arrangement of apparatus it is suggested that all theSounders uppermost in the diagram of the telegraph system, to wit,.thesounders 24 24:, 24*, 24 and 24: may be adjusted with their respectivecondensers in resonant responsiveness to periodic current of oneparticular frequency which may he commonly produced by allof thealternating current generator armatures which are uppermost in thediagram, to wit, the armatures 14 14, 14 14 and li while all theSounders-lowermost in the diagram may similarly respond to a commonerator armatures which are lowermost the diagram.

When the operator at one station is send ing with one of his sendingkeys, the

sounder at his own station which is respom sive to such sending key maybe cutout of circuit to economize the sending current. For instance, ifthe operator at M is sending a message with his sending key 17", he mayopen his sounder controlling switch 26 so as to cut out his sounder 2and avoid waste of the sending current controlled hy the key 17 whichsending current will then proceed along the third-rail section P M andalongthe continuous track rail to those sounders resonantly. responsiveto such current on one or hoth of the trains K and L, it is desired tosend this message simultaneously to tooth trains K and L, the operatorson both such trains 26" and 526 closed so as to maintain in circuittheir respective sounders 249 and 24, both resonantly responsive to suchcurrent. But if it is desired to send such message to the train K only,then the operator-on the train L will open his sounder-controllingswitch 26. Now, it is quite apparent that while the foregoing message isbeing sent by the key 17 at the fixed station 1V, another message may besent from such fixed station by the key 13, and will operate one or bothof the sounders 18 and 18 on the trains K and L, accordingly as one orboth of these sounders are included in circuit through their respectivesounder controlling switches'20 and 20. Or, while the first mentionedmessage is' being sent through the sending key 17" at thestation M, thesending key 13 at such' station may be left open and such station mayreceive a simultaneous message from either of the trains K or L, forinstance, from the train K whose operator will send out the messagethrough his sending key 13*, thus delivering to the third-rail section 3M and to the continuous track rail Pl, a periodic current which willefi'ect resonant response of the sounder 18 at the fixed station M, andwhich, incidentally, will also efiect resonant response of the sounder 1-8 on the train L, if the operator of such train has closed his soundercontrolling switch 20 to receive such message from the sending key 13 onthe train Such examples of the use of my system might be largelymultiplied but it is surficient to state that a given sending key can beemployed to deliver messages simultaneously to one or all of thestations of the telegraph system which are included in one third-railsection or telegraph section" in common with such given sending key; andthat any other sending key included in the same telegraph block orsection and control ling a periodic current of di fierent frequency maybe similarly employed at the same time. However, if it were desired tosend separate messages to a large number of trains all operating on onethird-rail section, a large number of different periodic currents wouldhave to be employed, and to avoid this necessity is one object which Ihave in View in dividing the third-rail into separate telegraph blocksor sections, each telegraph block being restricted to such length ofrailway track as will be ordinarily occupied by a comparatively smallnumber of separate railway trains or vehicles. Since the third-railsections are substantially isolated as regards interchange of theperiodic telegraph currents, such currents of the same frequency maybeemployed without interference in adjacent third-rail sections or blocks,the telegraph current applied to one third-rail section hememe-r ing notelfectually transmitted to the adjacent third-rail sections. atthestation Q; may employ his sending key 17 to transmit intelligencethrough the medium of the sounder 24: on the train N. without affectingthe sounders 24*, 24:, and 24", responsive to telegraph current of thesame frequency but located in a difl erent third-rail section. It willbe noted that the condensers such as 11 and 15 in series with thegenerator armatures of the motor generators of the telegraph system,prevent unidirectional motive power current from passing through suchgenerator armatures.

If desired each telegraph block or section of my system may include afixed station attended by an operator in constant communication with thetrain despatcher through the medium of the ordinary traindespatchingtelegraph system, and thereby the train despatcher will be in constantcommunicationwith every train on his di vision. A train may be recalledafter it has passed a railway station or after passing a railway stationthe train may receive orders to stop and take an. isolated siding topermit another train to pass. Wrecks and stoppages of the trains may beimmediately reported from isolated points, and in short many greatadvantages can be realized from the use of my invention.

It will be apparent that an overhead trolley wire may be employed inlieu of a thirdrail. Since alternating currentis a well known substitutefor unidirectional traction current, it may be noted that if thetraction generator p is to deliver an alternating current it will bewell to omit the impedance coils p 30 32 30, 3%, etc, and feed thethird-rail or trolley wire direct from the traction generator withoutany interposition of impedance coils which would more or less impair thetransmission of the alternating'tra-ction current. lln this event thethird-rail or trolley wire will constitute a single continuous telegraphconductor such for'instance as exemplified in the third-rail section P Mwith the impedance coil p omitted. All mowing and fixed stations of thetelegraph system will then commonly operate upon such single continuousmotional telegraph conductor, it being only necessary to employtelegraph current differi'ng in frequency from the alternating tractioncurrent and efiecting resonant or selective response of the telegraphSounders or receiving instruments. Indeed, as to the broad aspect of myinvention, it is sufi'icient that the traction current and the telegraphcurrent or currents be different in character and, although I haveparticularly described the employment of unidirectional traction currentand alternating telegraph current, I do not wish to be limited to thisparticular choice or arrangement of currents since it is Thus theoperator perfectly obvious that the arrangement may be reversed orotherwise modified.

What I claim and desire to secure by Letters Patent is j l. A railwaysignaling system comprising a signaling apparatus and a signalingcircuit in control of the signaling apparatus and including the trafficrails of the railway track and a source of signalin currentcharacterized by a periodic variatlon of distinctive frequency andincluding inductance and capacity adjusted substantially in resonancewith the periodic variation of the signaling current.

2. A railway electric signaling system comprising a section of railwaytrack, a source of, periodic signaling current connected with the railsof the section, a selfinductive electro-translative device and consourceof periodic signaling current arranged to deliver such current to therails of the section, a self-inductive electro-translative device andcondenser connected together and relatively adjusted substantially inresonance with the frequency of the periodic signaling current andarranged to receive electrical energy of such frequency from the railsof the section, and a signaling apparatus controllable by theelectrostranslative device.

4. A railway electric signaling system comprising a section of a railwaytrack, a source of periodic signaling current arranged to deliver suchcurrent to the rails of the section, a self-inductiveelectro-translative device and a condenser connected in series acrossthe rails of the section and relatively adjusted substantially inresonance with the frequency-of the periodic signaling current, andsignaling apparatus controllable by the electro-translative device.

In testimony whereof I have affixed my signature in presence of twowitnesses.

- ALBERT V. T. DAY.' Witnesses:

HENRY D. WILLIAMS, BERNARD Gown.

